The present invention relates to an apparatus for compressing and heating a material to be treated, i.e., fibrous materials of plants such as, for example, true grasses or the like, changing the quality of the material to be treated, and solidifying the same and, more particularly, to a control system for the apparatus which enables such treatments to be carried out in a continuous and stable manner.
Heretofore, the presence of large amounts of silicates in the stems, branches and leaves as well as the outer covering of seeds of true grasses, particularly in the husks, has prevented these materials from being utilized as fodder for cattle, horses and sheep and fertilizers for plants. The fact is that the husks produced in large volumes by paddy huskers at the grain conditioning stage are dumped and piled out of doors. Since the husks do not undergo decomposition, it is impossible to make effective use of the land where the husks are dumped, and there is a risk of occurrence of fire. It is generally considered a best solution to the problem to artificially or unnaturally burn the husks. However, to burn the husks in large volumes would give rise to the problem of air pollution with smoke and dust.
Japanese Patent Publication No. 57-31943 discloses a method of processing a material to be treated such as outer covering of seeds, stems, branches and leaves of true grasses containing large amounts of silicates. The method consists in feeding the material to be treated into a space which is in the form of a spiral at its inner or outer surface and which has a cross-sectional area successively decreasing, destroying the molecular structure of the material under a pressure of 1-100 tons per 1 cm.sup.2 and at a temperature of 150-600.degree. C., and solidifying the material to be treated. The solidified material can be used as a fuel without any further processing or can be crushed into smaller particles for use as industrial material or as fodder for cattle, horses and sheep. However, no apparatus has ever been developed which is capable of satisfactorily carrying into practice the method disclosed in the Japanese patent publication referred to above.